#pragma once
#include<iostream>
#include<vector>
#include<assert.h>
using namespace std;

template<class K, class V>
struct AVLTreeNode
{
	pair<K, V> _kv;
	AVLTreeNode<K, V>* _left;
	AVLTreeNode<K, V>* _right;
	AVLTreeNode<K, V>* _parent;
	int _bf;

	AVLTreeNode(const pair<K, V>& kv)
		:_kv(kv)
		, _left(nullptr)
		, _right(nullptr)
		, _parent(nullptr)
		, _bf(0)
	{}
};

template<class K, class V>
class AVLTree
{
	typedef AVLTreeNode<K, V> Node;
public:
	AVLTree() = default;

	bool Insert(const pair<K, V>& kv)
	{
		if (_root == nullptr)
		{
			_root = new Node(kv);
			return true;
		}

		Node* parent = nullptr;
		Node* cur = _root;
		while (cur)
		{
			if (cur->_kv.first < kv.first)
			{
				parent = cur;
				cur = cur->_right;
			}
			else if (cur->_kv.first > kv.first)
			{
				parent = cur;
				cur = cur->_left;
			}
			else
			{
				//找到相同的数，返回false
				return false;
			}
		}
		//插入新节点
		cur = new Node(kv);
		if (parent->_kv.first < kv.first)
		{
			parent->_right = cur;
		}
		else
		{
			parent->_left = cur;
		}
		cur->_parent = parent;//与parent链接

		//更新平衡因子
		while (parent)
		{
			if (cur == parent->_left)
			{
				parent->_bf--;
			}
			else
			{
				parent->_bf++;
			}

			if (parent->_bf == 0)//平衡，不需要更新
			{
				break;
			}
			else if (parent->_bf == 1 || parent->_bf == -1)
			{
				//高度产生变化了，需要往上更新
				//继续往上更新
				cur = parent;
				parent = parent->_parent;
			}
			else if (parent->_bf == 2 || parent->_bf == -2)
			{
				//加剧了不平衡，需要旋转
				if (parent->_bf == 2 && cur->_bf == 1)
				{
					RotateL(parent);
				}
				else if (parent->_bf == -2 && cur->_bf == -1)
				{
					RotateR(parent);
				}
				else if (parent->_bf == -2 && cur->_bf == 1)
				{
					RotateLR(parent);
				}
				else
				{
					RotateRL(parent);
				}
				break;
			}
			else
			{
				assert(false);
			}
		}

		return true;
	}

	Node* Find(const K& kv)
	{
		Node* cur = _root;
		while (cur)
		{
			if (cur->_kv.first < kv)
			{
				cur = cur->_right;
			}
			else if (cur->_kv.first > kv)
			{
				cur = cur->_left;
			}
			else
			{
				return cur;
			}
		}
		return nullptr;
	}

	// AVL树的验证
	bool IsAVLTree()
	{
		return _IsAVLTree(_root);
	}

	int Height()
	{
		return _Height(_root);
	}

	void InOrder()
	{
		return _InOrder(_root);
	}

	int Size()
	{
		return _Size(_root);
	}

private:
	int _Size(Node* root)
	{
		return root == nullptr ? 0 : _Size(root->_left) + _Size(root->_right) + 1;
	}

	// 根据AVL树的概念验证pRoot是否为有效的AVL树
	bool _IsAVLTree(Node* root)
	{
		if (nullptr == root)
		{
			return true;
		}

		int leftHeight = _Height(root->_left);
		int rightHeight = _Height(root->_right);
		int diff = rightHeight - leftHeight;

		if (abs(diff) >= 2)
		{
			cout << root->_kv.first << "高度差出现异常" << endl;
		}

		if (root->_bf != diff)
		{
			cout << root->_kv.first << "平衡因子出现异常" << endl;
		}

		return _IsAVLTree(root->_left) && _IsAVLTree(root->_right);
	}

	void _InOrder(Node* root)
	{
		if (root == nullptr)
			return;

		_InOrder(root->_left);
		cout << root->_kv.first << ":" << root->_kv.second << endl;
		_InOrder(root->_right);
	}

	int _Height(Node* root)
	{
		if (root == nullptr)
			return 0;

		int leftHeight = _Height(root->_left);
		int rightHeight = _Height(root->_right);

		return leftHeight > rightHeight ? leftHeight + 1 : rightHeight + 1;
	}

	void RotateL(Node* parent)
	{
		_rotateNum++;

		Node* subR = parent->_right;
		Node* subRL = subR->_left;

		parent->_right = subRL;
		if (subRL)
			subRL->_parent = parent;

		Node* parentParent = parent->_parent;

		subR->_left = parent;
		parent->_parent = subR;

		if (parentParent == nullptr)
		{
			_root = subR;
			subR->_parent = nullptr;
		}
		else
		{
			if (parent == parentParent->_left)
			{
				parentParent->_left = subR;
			}
			else
			{
				parentParent->_right = subR;
			}
			subR->_parent = parentParent;
		}
		parent->_bf = subR->_bf = 0;
	}

	// 右单旋
	void RotateR(Node* parent)
	{
		_rotateNum++;

		Node* subL = parent->_left;
		Node* subLR = subL->_right;

		parent->_left = subLR;
		if (subLR)
			subLR->_parent = parent;

		Node* parentParent = parent->_parent;

		subL->_right = parent;
		parent->_parent = subL;

		//判断是否为根？
		if (parentParent == nullptr)
		{
			_root = subL;
			subL->_parent = nullptr;
		}
		else
		{
			if (parent == parentParent->_left)
			{
				parentParent->_left = subL;
			}
			else
			{
				parentParent->_right = subL;
			}

			subL->_parent = parentParent;
		}
		parent->_bf = subL->_bf = 0;
	}

	void RotateRL(Node* parent)
	{
		_rotateNum++;

		Node* subR = parent->_right;
		Node* subRL = subR->_left;
		int bf = subRL->_bf;

		RotateR(parent->_right);
		RotateL(parent);

		//更新平衡因子
		if (bf == 0)
		{
			subR->_bf = 0;
			subRL->_bf = 0;
			parent->_bf = 0;
		}
		else if (bf == 1)
		{
			subR->_bf = 0;
			subRL->_bf = 0;
			parent->_bf = -1;
		}
		else if (bf == -1)
		{
			subR->_bf = 1;
			subRL->_bf = 0;
			parent->_bf = 0;
		}
		else
		{
			assert(false);
		}
	}

	void RotateLR(Node* parent)
	{
		_rotateNum++;

		Node* subL = parent->_left;
		Node* subLR = subL->_right;
		int bf = subLR->_bf;

		RotateL(parent->_left);
		RotateR(parent);

		if (bf == 0)
		{
			subL->_bf = 0;
			subLR->_bf = 0;
			parent->_bf = 0;
		}
		else if (bf == -1)
		{
			subL->_bf = 0;
			subLR->_bf = 0;
			parent->_bf = 1;
		}
		else if (bf == 1)
		{
			subL->_bf = -1;
			subLR->_bf = 0;
			parent->_bf = 0;
		}
		else
		{
			assert(false);
		}
	}

private:
	Node* _root = nullptr;

public:
	int _rotateNum = 0;
};


void AVLTreetest1()
{
	AVLTree<int, int> t;
	int a[] = { 16,3,7,11,9,26,18,14,15 };
	//int a[] = { 4,2,6,1,3,5,15,7,16,14 };
	for (auto e : a)
	{
		/*	if (e == 11)
			{
				int i = 0;
			}*/
		t.Insert({ e,e });
		//cout << e << "->" << t._IsBalanceTree() << endl;

	}
	t.InOrder();
	cout << t.IsAVLTree();
}